Handlebar Grips Slipping

Especially when it rains, and even when it doesn't, my grips rotate. Is there anything I can do, without causing a pain later, to keep them from slipping? I'm hesitant to squirt some adhesive in there because then I'll have to scrape it all off if I switch grips.

What bike and what grips? Aren't some of the Trek FX bars not standard, smaller than standard after market grips? I have no familiarity with this personally but seems like it has been mentioned on BF before.

The old school method I know of, if there aren't any screws to hold them, is to remove the grips and use hair spray when reinstalling them. Let them sit over night to dry.

^^^ THIS ^^^

I've used the Aqua-Net method for ~30 years. Dirt cheap, and it works as well to hold a pair of Ourys now as it did to hold a pair of ODI Mushrooms back in the day.
Heck, I even suggest it to my field technicians now when they're working on re-gripping elliptical machines and stationary bikes.

"I feel like my world was classier before I found cyclocross."
- Mandi M.

I use plain old rubbing alcohol, clean the bars, drip some alcohol into the grip itself, cover the hole with my finger shake it up inside the grip and slide it on, then let it dry over night and I have never had grips slip after doing that.